inject SkUserConfig.h with -DSK_USER_CONFIG_HEADER

This lets clients explicitly declare which SkUserConfig.h
to use, rather than implictly via include directory priority.

See include/gpu/gl/GrGLConfig.h for a similar setup.

Looks like keeping an #else case around is going to be the
easiest way to keep Android building, unless I can find a
way to push -DSK_USER_CONFIG_HEADER up to Skia's reverse
dependencies.

Change-Id: I9c297324cbafbd5f0d1a3dc1c90f0ceae0339e88
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209866
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
1 file changed